Typically, a relatively large handle effort is required to open a cab door of a construction machine. Contributing factors can include low mechanical advantage offered by current handle designs and existence of friction between components of a latch. For example, U.S. Pat. No. 5,117,665 relates to a vehicle door lock system including interior and exterior handle assemblies that are accessible, respectively, from interior and exterior sides of a vehicle door. The door lock system includes a rotary latch that is configured to releasably engage a door-frame-mounted striker to “latch” and “unlatch” the door. The door is “locked” and “unlocked” by selectively enabling and disabling driving connections between the handle assemblies and separate release arms of the rotary latch. More specifically, locking and unlocking of the door are affected either by operating an exterior key cylinder, or by operating an interior sill button.